This application is a request for support for a symposium entitled "MECHANISMS OF OOCYTE MATURATION AND FERTILIZATION" that Professor Motonori Hoshi and I have organized for the Seventh International Congress of Invertebrate Reproduction and Development (ICIR7). This triennial Congress will be held August 5 - 11, 1995 in Santa Cruz, California. The Congress always has a broad international audience, and the speakers who have already accepted the invitation from Prof. Hoshi and me include investigators from Japan, France, USA, Canada, Russia, Italy, and Mexico. Description of the symposium: Mechanisms mediating oocyte maturation and fertilization, proceeding from hormone or sperm interaction with the membrane through the secondary membrane and intracellular events that follow, are still poorly defined. In some invertebrate systems (sea urchins, abalone, etc.) there has been impressive recent progress in defining components mediating sperm-oocyte interactions. Although there have been many advances in the discovery of intracellular 'initiators' of maturation, which include maturation promoting factor (MPF) and other proteins, the receptor mechanisms and initial mediating steps are controversial. With regard to intracellular events, recent reports indicate possible roles (and controversy) for calcium, cyclic AMP, inositol phosphates, diacylglycerol from inositol or choline lipid metabolic pathways, phospholipase A2, pH, G proteins (possible controversy concerning which subunits), arachidonic acid metabolites, protein kinase C, etc. The time is right for various workers in this field of research to come together to discuss recent progress and the relevance and importance of differences in their respective experimental systems. Invited speakers have all made recent important contributions to the field, working on invertebrate systems. In addition, one or two speakers who work on vertebrate systems will also participate to compare and contrast putative mechanisms, and to give a greater perspective on the utility of invertebrate preparations as model systems for understanding general mechanisms of fertilization and oocyte maturation. Funds are requested for partial support of travel, registration, meals and lodging expenses. The registration fee includes the cost of publishing symposium presentations. Since travel expenses for the Congress, particularly for foreign investigators, are very high, many invited speakers have indicated that their acceptance depends upon substantial funding of their expenses. The Congress will publish full length refereed symposium papers in a proceedings volume appearing within a year of the Congress, published through their journal (Invertebrate Reproduction and Development), as used for ICIR6. Interactions of the speakers at the meeting and publication of full length papers from this symposium will bring investigators up to date on these important topics and should have an important impact on progress in the field.